Bone Microarchitecture Is Impaired in Adolescent Amenorrheic Athletes Compared with Eumenorrheic Athletes and Nonathletic Controls

Ackerman KE, Nazem T, Chapko D, Russell M, Mendes N, Taylor AP, Bouxsein ML, Misra M. J Clin Endocrinol Metab. 2011 Aug 3. [Epub ahead of print]

Dual-energy x-ray absorptiometry (DEXA) is the most common modality used in the assessment of bone health. Some studies have suggested that quantitative assessment of bone microarchitecture may be a more sensitive measure of fracture risk. Adolescence and young adulthood are critical time periods for developing peak bone mass. In this study, the authors hypothesized that bone microarchitecture is impaired in adolescent and young adult amenorrheic athletes (absence of menses for at least 3 months in 6 month period, or absence of menarche at age 16) compared to eumenorrheic athletes (having at least 9 menses in past year) and non-athletic controls. All three groups had bone mineral density (BMD) assessed by DEXA at the spine and hip. Bone microarchitecture was assessed by high-resolution peripheral quantitative computed tomography (HRpQCT) at the ultradistal radius (non-weight bearing bone) and the tibia (weight-bearing bone). As expected, BMD Z-scores of the lumbar spine were lower in amenorrheic athletes in comparison to the other two groups, and femoral neck and hip BMD Z-scores were the highest in eumenorrheic athletes. As far as bone microarchitecture assessed by HRpQCT, amenorrheic athletes had lower total density of the tibia and radius, as well as lower cortical density in the tibia, and lower trabecular density in the radius. The authors report that athletic activity is associated with greater total trabecular area and cortical perimeter at the weight-bearing tibia. Amenorrhea is associated with lower trabecular bone density of the non-weight bearing radius, lower total density and trabecular number, and greater trabecular separation at the tibia.

The concern for these young women is that if they develop abnormal bone health now, not only are they at an immediate higher fracture risk, they are at risk of impaired bone health later in life. The authors cite several studies that suggest that abnormal bone microarchitecture may be possible when DEXA is normal and that microarchitecture may be a more sensitive measure for fracture risk. They conclude in their article that independent of bone mineral density, microarchitecture provides information about bone parameters in the amenorrheic athlete. Although more data is obtained from the HRpQCT study compared to DEXA, it’s not clear when it would be appropriate and/or helpful to order the HRpQCT in the clinical setting. Future studies could compare the HRpQCT and DEXA data in individual patients to see how often abnormal bone microarchitecture is found in patients with a normal DEXA scan. A cost-benefit analysis could then be performed to determine if the increased sensitivity is worth the increased radiation exposure and higher cost. Clinically, these results are interesting because we often have a difficult time counseling our amenorrheic athletes regarding the dangers of amennorhea. Laboratory data and DEXA results are often normal in this patient population. Data from HRpQCT could provide objective data regarding distortion of bone architecture and information that may help female athletes with amenorrhea realize the possible risks they are taking with their bodies now and for the future. What is your experience with amenorrheic athletes and bone injury? Is this more difficult to deal with if you are male? What strategies do you use?

Written by: Kris Fayock, MD and Marc Harwood, MD
Reviewed by: Stephen Thomas